1. Field of the Invention
The invention relates to methods and apparatus for transferring articles and, more particularly, transferring articles from first rows of such articles having a first row spacing and an initial row orientation to second rows of said articles having a second row spacing and the same initial row orientation relative to the second rows.
2. Description of the Prior Art
Semiconductor devices, such as integrated circuits, must be connected to external circuits. One method of doing this involves first bonding the integrated circuit to a small piece of ceramic, about 0.2 inches square, termed a miniceramic, having a pattern of conductive material deposited thereon and, then, bonding leads suitable for connection to external circuits to the conductive pattern. Thus, the ceramic supports the integrated circuit and relieves it from stresses exerted by external forces on the leads.
The bonding of the leads to the conductive pattern would be tedious, time consuming and costly if done individually. These deficiencies are avoided by mass bonding. See, for example, U.S. Pat. No. 3,94l,297 which issued to J. A. Burns and A. R. Sivo, Mar. 2, 1976 and is assigned to the same assignee as the instant application. However, the miniceramics must be quickly and precisely positioned in the mass bonding apparatus; for example, positioned on an insert assembly of the above-mentioned Burns et al. patent. To do this, the miniceramics must be removed from handling trays or magazines used throughout processing, wherein they abut each other in close parallel rows, and transferred to the anvil assembly where they have a widely spaced nonabutting relationship and the same row orientation as in the magazines.
In the ceramic art, kiln loaders and unloaders, as disclosed, for example in U.S. Pat. No. 3,360,102, issued to H. B. Cummings, Dec. 26, 1967 and U.S. Pat. No. 3,601,243, issued to S. S. Gurgacz, Aug. 24, 1974, may be used to transfer multiple ceramic pieces or the like from a conveyor belt to the kiln conveyor and/or vice versa. The pieces may be widely spaced on the conveyor belt but must be closely spaced on the kiln conveyor to achieve maximum kiln capacity. A pivoting vacuum pickup arm is used to remove the ceramic pieces from the conveyor belt and deposit them on the kiln conveyor. The arm includes a lazy-tong mechanism to expand or contract the distance between vacuum pickups while the arm pivots from a parallel position over one conveyor to an angular position over the other conveyor. There is no need to maintain the row orientation of, or precisely position, the pieces on either conveyor and the orientation is not maintained.
In the semiconductor art, on the other hand, the row orientation of miniceramics must be precisely maintained and the miniceramics precisely positioned for mass bonding. In addition, mechanisms for changing spacing should be avoided in order to eliminate inaccuracies introduced by play in the mechanism, if precision of positioning is to be maintained.